Soil erosion control and water resource protection can closely interact during restoration of terrestrial ecosystems. In semi‐arid ecosystems, an urgent issue is how vegetation restoration can ...achieve the goal of soil erosion mitigation and water conservation, which in turn, feeds back to ecosystem functioning.
We reviewed 78 articles from 22 countries in semi‐arid areas to evaluate the effects of vegetation type (i.e. forest, grassland and scrubland) on runoff and sediment yields across different environmental conditions (i.e. vegetation coverage, rainfall intensity, slope gradient and soil texture).
Our meta‐analysis shows that runoff and sediment reduction both increased as the vegetation coverage increased, and tended to be stable when vegetation coverage exceeded 60%. Vegetation provided a greater benefit for sediment reduction than for runoff control under intense rainfall. Grasslands were generally more effective in reducing sediment than other vegetation types. Forests, grasslands and scrublands were most efficient in soil erosion control on 20°–30°, 0°–25° and 10°–25° slopes respectively. Grasslands and scrublands generally performed better with respect to soil erosion control on moderately coarse soils, whereas forests were most effective on medium‐textured and moderately fine soils.
Synthesis and applications. Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates that, for land managers, it is critical to consider local slope, and soil texture, and maintain appropriate vegetation coverage to achieve ecosystem sustainability. Grasslands might be particularly suitable to optimize the trade‐off between soil erosion control and surface water resource in semi‐arid regions.
抽象
半干旱区水保型植被恢复过程中如何实现水土流失控制且维系地表水资源的目标，并进一步反馈于植被生态系统功能，是目前亟待解决的问题。
本研究基于公开发表的来源于22个国家、78篇关于半干旱区植被对土壤侵蚀影响的文献报道，应用Meta‐analysis方法，系统评价了不同植被类型（林地，草地和灌木地）在不同环境条件（植被盖度、降雨强度、坡度和土壤质地）下对径流量和产沙量的影响。
研究结果表明，植被减流效应和减沙效应均随植被盖度的增加而增加，并在植被盖度达到60%时趋于稳定。强降雨下，植被减沙效应大于其减流效应。总体上，三种植被类型中，草地具有最高的减沙效应。林地、草地和灌木地分别在20°‐30°、0°–25°和10º‐25°坡度范围内表现出较高的减流效应和减沙效应。且草地和灌木地在中等粗糙质地土壤中的减流效应和减沙效应较高，林地在中等质地和中等细密质地土壤中的减流效应和减沙效应较高。
综合应用：半干旱区的水保型植被水土流失调控的有效性很大程度上取决于适宜的植被类型。本研究表明，在全球半干旱区，建设草地植被可有效实现水土流失调控与地表水资源维系的权衡。同时，在水保型植被建设过程中，应综合考虑坡度和土壤质地等实际情况并维持适宜的植被盖度，以实现植被生态系统的可持续性。
Effective restoration and soil erosion control in semi‐arid ecosystems strongly depends on the selection of vegetation type. Our study further indicates that, for land managers, it is critical to consider local slope, and soil texture, and maintain appropriate vegetation coverage to achieve ecosystem sustainability. Grasslands might be particularly suitable to optimize the trade‐off between soil erosion control and surface water resource in semi‐arid regions.
Margin theory provides one of the most popular explanations to the success of AdaBoost, where the central point lies in the recognition that margin is the key for characterizing the performance of ...AdaBoost. This theory has been very influential, e.g., it has been used to argue that AdaBoost usually does not overfit since it tends to enlarge the margin even after the training error reaches zero. Previously the minimum margin bound was established for AdaBoost, however, Breiman (1999) 9 pointed out that maximizing the minimum margin does not necessarily lead to a better generalization. Later, Reyzin and Schapire (2006) 37 emphasized that the margin distribution rather than minimum margin is crucial to the performance of AdaBoost. In this paper, we first present the kth margin bound and further study on its relationship to previous work such as the minimum margin bound and Emargin bound. Then, we improve the previous empirical Bernstein bounds (Audibert et al. 2009; Maurer and Pontil, 2009) 2,30, and based on such findings, we defend the margin-based explanation against Breimanʼs doubts by proving a new generalization error bound that considers exactly the same factors as Schapire et al. (1998) 39 but is sharper than Breimanʼs (1999) 9 minimum margin bound. By incorporating factors such as average margin and variance, we present a generalization error bound that is heavily related to the whole margin distribution. We also provide margin distribution bounds for generalization error of voting classifiers in finite VC-dimension space.
Small interfering RNA (siRNA) is an effective therapeutic to regulate the expression of target genes in vitro and in vivo. Constructing a siRNA delivery system with high serum stability, especially ...responsive to endogenous stimuli, remains technically challenging. Herein we develop anti-degradation Y-shaped backbone-rigidified triangular DNA bricks with sticky ends (sticky-YTDBs) and tile them onto a siRNA-packaged gold nanoparticle in a programmed fashion, forming a multi-functional three-dimensional (3D) DNA shell. After aptamers are arranged on the exterior surface, a biocompatible siRNA-encapsulated core/shell nanoparticle, siRNA/Ap-CS, is achieved. SiRNAs are internally encapsulated in a 3D DNA shell and are thus protected from enzymatic degradation by the outermost layer of YTDB. The siRNAs can be released by endogenous miRNA and execute gene silencing within tumor cells, causing cell apoptosis higher than Lipo3000/siRNA formulation. In vivo treatment shows that tumor growth is completely (100%) inhibited, demonstrating unique opportunities for next-generation anticancer-drug carriers for targeted cancer therapies.
Abstract
The biodiversity–ecosystem functioning relationship has received significant attention in recent decades. It has been widely demonstrated that plant diversity plays a crucial role in ...enhancing the functioning of terrestrial ecosystems. However, few studies have tested the influence of plant species richness in mediating the impacts of climate on ecosystem functions at large spatial scales.
To address this gap, we utilized data from field surveys across broad climatic gradients at the Qinghai–Tibetan Plateau, China. Our goal was to examine the importance of plant species richness for the functioning of alpine grassland ecosystems, specifically productivity and soil carbon sequestration.
Our results showed strong positive correlations between ecosystem functioning and growing season precipitation as well as species richness. In contrast, there was a negative correlation with growing season temperature. Notably, the positive effect of growing season precipitation on ecosystem functioning outweighed the negative effect of growing season temperature. The indirect effects of growing season precipitation and temperature on ecosystem functioning through changes in species richness were weak. Furthermore, the inclusion of climate factors in the model weakened the relationships between species richness and ecosystem functioning.
Synthesis
. Our findings demonstrate that climate factors are more important than species richness for the provisioning of ecosystem functions at large spatial scales. In summary, our study underscores the importance of considering climate factors alongside species richness when assessing ecosystem functioning across extensive geographical areas.
摘要
近几十年来，生物多样性与生态系统功能的关系备受关注。众多研究广泛报导了植物多样性在增强陆地生态系统功能方面发挥着至关重要的作用。然而，很少有研究在大空间尺度上测试植物物种丰富度在调节气候对生态系统功能影响方面的作用。
为了填补这一空白，我们利用青藏高原东缘跨气候梯度的野外调查数据研究了植物物种丰富度对高寒草地主要生态系统功能的作用，尤其是生产力和土壤碳固存。
研究结果表明草地生态系统功能与生长季降水和物种丰富度呈显著正相关，而与生长季温度呈负相关。值得注意的是，生长季降水对高寒草地生态系统功能的积极影响超过生长季温度的消极影响。生长季降水和温度通过调节物种丰富度变化对高寒草地生态系统功能的间接影响较弱。此外，将气候因子纳入模型削弱了物种丰富度与生态系统功能之间的关系。
综述:研究结果表明在大空间尺度上，气候因子(降水和温度)比物种丰富度对草地生态系统功能维持的贡献更大。总之，我们的研究强调在评估大区域的生态系统功能时，需同时考虑物种丰富度和气候因子的重要性。
•Soil erosion control benefit of grasslands and forests are evaluated.•Soil erosion control benefit tends to be stable when vegetation cover exceeds 60%•Sediment reduction is more sensitive than ...runoff control to rainfall intensity.•Forests and grasslands have the best soil erosion control on 20–25° and 15–20° slopes.•Grassland and understory grassland must be promoted in afforestation.
Afforestation reduces soil loss and minimizes landslide risk worldwide, but little is known on the effectiveness of afforestation policies to control soil erosion with different vegetation types in semi-arid areas. Understanding the effectiveness of distinct re-vegetation types under different physiographic conditions (slope gradient, percentage of vegetation cover and rainfall depth) is essential for better policy formulation. This study examines the benefits of soil erosion control in forests and grasslands using published data. This analysis proves that the benefits of vegetation restoration increase with increasing the vegetation cover and tend to be stable when the coverage exceeds 60%. The benefits on sediment yield reduction are more sensitive (vs. runoff reduction benefit) to rainfall intensity. Regarding slopes and soil erosion control, the highest efficiencies appear in forests on 20–25° slopes and in grasslands on 15–20° slopes. Grasslands can effectively reduce soil erosion, as well as forests with understory grasses. For long-term restoration, a 60% vegetation cover maximizes the benefits of reducing soil erosion and maintaining enough soil water supply that prevents possible soil drought. We propose that future afforestation policies should evaluate in advance the appropriate re-vegetation type; meanwhile, suitable vegetation coverage and local physiographic conditions should be considered. Importantly, promotion of grassland and preservation of forest understory grasses must be enforced in land use policies when considering afforestation to minimize soil erosion. We suggest further research to quantify the efficiency of understory vegetation on soil erosion control, which might provide scientific and practical guidance for afforestation policy in semi-arid areas.
Fast Multi-Instance Multi-Label Learning Huang, Sheng-Jun; Gao, Wei; Zhou, Zhi-Hua
IEEE transactions on pattern analysis and machine intelligence,
2019-Nov.-1, 2019-Nov, 2019-11-1, 20191101, Letnik:
41, Številka:
11
Journal Article
Recenzirano
Odprti dostop
In many real-world tasks, particularly those involving data objects with complicated semantics such as images and texts, one object can be represented by multiple instances and simultaneously be ...associated with multiple labels. Such tasks can be formulated as multi-instance multi-label learning (MIML) problems, and have been extensively studied during the past few years. Existing MIML approaches have been found useful in many applications; however, most of them can only handle moderate-sized data. To efficiently handle large data sets, in this paper we propose the MIMLfast approach, which first constructs a low-dimensional subspace shared by all labels, and then trains label specific linear models to optimize approximated ranking loss via stochastic gradient descent. Although the MIML problem is complicated, MIMLfast is able to achieve excellent performance by exploiting label relations with shared space and discovering sub-concepts for complicated labels. Experiments show that the performance of MIMLfast is highly competitive to state-of-the-art techniques, whereas its time cost is much less. Moreover, our approach is able to identify the most representative instance for each label, and thus providing a chance to understand the relation between input patterns and output label semantics.
The integration of porous metal-organic frameworks onto the surface of materials, for use as functional devices, is currently emerging as a promising approach for gas sensing and flexible displays. ...However, research focused on potential applications in electronic devices is in its infancy. Here we present a facile strategy by which interpenetrated, crystalline metal-organic framework films are deposited onto conductive metal-plate anodes via in situ temperature-controlled electrochemical assembly. The nanostructure of the surface as well as the thickness and uniformity of the film are well controlled. More importantly, the resulting films exhibit enhanced dielectric properties compared to traditional inorganic or organic gate dielectrics. This study demonstrates the successful implementation of the rational design of metal-organic framework thin films on conductive supports with high-performance dielectric properties.
Multi-label learning has attracted much attention during the past few years. Many multi-label approaches have been developed, mostly working with surrogate loss functions because multi-label loss ...functions are usually difficult to optimize directly owing to their non-convexity and discontinuity. These approaches are effective empirically, however, little effort has been devoted to the understanding of their consistency, i.e., the convergence of the risk of learned functions to the Bayes risk. In this paper, we present a theoretical analysis on this important issue. We first prove a necessary and sufficient condition for the consistency of multi-label learning based on surrogate loss functions. Then, we study the consistency of two well-known multi-label loss functions, i.e., ranking loss and hamming loss. For ranking loss, our results disclose that, surprisingly, none of convex surrogate loss is consistent; we present the partial ranking loss, with which some surrogate losses are proven to be consistent. We also discuss on the consistency of univariate surrogate losses. For hamming loss, we show that two multi-label learning methods, i.e., one-vs-all and pairwise comparison, which can be regarded as direct extensions from multi-class learning, are inconsistent in general cases yet consistent under the dominating setting, and similar results also hold for some recent multi-label approaches that are variations of one-vs-all. In addition, we discuss on the consistency of learning approaches that address multi-label learning by decomposing into a set of binary classification problems.
The application of ecological restoration programs, related to water resources protection and soil erosion control, may have some undesirable outcomes. An important example is the effect that ...vegetation restoration may have in reducing surface water resources. After searching peer-reviewed articles, we selected 38 publications from 16 countries in comparable areas - semiarid conditions (aridity index <0.5), surface coverage >50% and fine soil texture - to evaluate the effectiveness of different types of vegetation (i.e., forestland, scrubland and grassland) in regulating runoff and sediment transport. In particular, we used three indices: the runoff reduction effect, the sediment reduction effect and the ratio between runoff and sediment reduction. These indices were calculated from measured data reported in the original articles. Results showed that scrubland had higher runoff reduction effect (59% in gentle slopes; 65% in steep slopes) than in grassland (39% on gentle slopes; 43% on steep slopes) and forestland (33% on gentle slopes; 51% on steep slopes). For the three types of vegetation, the sediment reduction effect was >70%. Concerning the ratios between runoff and sediment reduction, grassland showed the lowest ratios (56% on gentle slopes; 53% on steep slopes) compared to forestland (63% on gentle slopes; 65% on steep slopes) and scrubland (93% on gentle slopes; 81% on steep slopes). Our results indicate that low values of ratios between runoff and sediment reduction are the most suitable because they indicate an effective soil erosion and sediment delivery reduction but maintaining surface runoff. Overall, our study demonstrates that grassland may be the best choice for optimizing the trade-off between catchment water yield and soil conservation during the implementation of ecological restoration programs in semi-arid regions.
Display omitted
•Effects of vegetation on soil erosion and water resources•Scrubland had a higher runoff reduction effect than grassland and forestland.•Sediment reduction in the three vegetation types was >70%.•Semi-arid grassland had lowest ratio between runoff and sediment reduction.•Grassland optimizes the trade-off between runoff maintenance and erosion reduction.
The senescence‐associated secretory phenotype (SASP) is a striking characteristic of senescence. Accumulation of SASP factors causes a pro‐inflammatory response linked to chronic disease. Suppressing ...senescence and SASP represents a strategy to prevent or control senescence‐associated diseases. Here, we identified a small molecule SR9009 as a potent SASP suppressor in therapy‐induced senescence (TIS) and oncogene‐induced senescence (OIS). The mechanism studies revealed that SR9009 inhibits the SASP and full DNA damage response (DDR) activation through the activation of the NRF2 pathway, thereby decreasing the ROS level by regulating the expression of antioxidant enzymes. We further identified that SR9009 effectively prevents cellular senescence and suppresses the SASP in the livers of both radiation‐induced and oncogene‐induced senescence mouse models, leading to alleviation of immune cell infiltration. Taken together, our findings suggested that SR9009 prevents cellular senescence via the NRF2 pathway in vitro and in vivo, and activation of NRF2 may be a novel therapeutic strategy for preventing cellular senescence.
The small molecule SR9009 counteracts cellular senescence induced by persistent DNA damage. The suppressive effects are mediated by inhibiting ROS level through the NRF2 pathway.
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